Ok. I just figured out the exhaust lobe centers. Here's the data that I have:
It looks like we can accurately say that your duration @ .050 is 187 for all lobes (they are all within +/- 1°).
For the spare engine:
Intake lobe center: 110.1°
Exhaust lobe center: 99.8°
Lobe Centerline: 104.9°
For the parts truck engine:
Intake lobe center: 108.6°
Exhaust lobe center: 101°
Lobe Centerline: 104.8°
The intake lobe centers and exhaust lobe centers for the spare engine are about 1.75° difference. This I contribute to them being the same cam, just installed 2° off. Especially since the lobe centers are within .1° of each other (how many degrees apart the intake lobe center and exhaust lobe center are).
The max lift of your cam is .251" which calculates to a lift of .377" at the valve after a 1.5 rocker arm ratio. Usually the measured lift is less that what the cam specs at, (usually the rocker arm ratio is 1.4 instead of 1.5). I would not be surprised if the factory lift was spec'ed near .400" lift or just under for this cam.
When I take my measurements on v-8's, I use solid lifter and adjustable pushrods at zero clearance to map my cams. I feel that the information is more accurate to take it at the valve than at the cam lobe. By measuring at the valve, you see what the rocker arm geometry is doing to the net lift and duration of the cam.
You did a good job for your first time. Your results do correlate pretty well, which shows that you took good data/numbers.
Now I have to figure out how to explain this to you without getting too confused myself or confusing you trying to explain it....
It looks like we can accurately say that your duration @ .050 is 187 for all lobes (they are all within +/- 1°).
For the spare engine:
Intake lobe center: 110.1°
Exhaust lobe center: 99.8°
Lobe Centerline: 104.9°
For the parts truck engine:
Intake lobe center: 108.6°
Exhaust lobe center: 101°
Lobe Centerline: 104.8°
The intake lobe centers and exhaust lobe centers for the spare engine are about 1.75° difference. This I contribute to them being the same cam, just installed 2° off. Especially since the lobe centers are within .1° of each other (how many degrees apart the intake lobe center and exhaust lobe center are).
The max lift of your cam is .251" which calculates to a lift of .377" at the valve after a 1.5 rocker arm ratio. Usually the measured lift is less that what the cam specs at, (usually the rocker arm ratio is 1.4 instead of 1.5). I would not be surprised if the factory lift was spec'ed near .400" lift or just under for this cam.
When I take my measurements on v-8's, I use solid lifter and adjustable pushrods at zero clearance to map my cams. I feel that the information is more accurate to take it at the valve than at the cam lobe. By measuring at the valve, you see what the rocker arm geometry is doing to the net lift and duration of the cam.
You did a good job for your first time. Your results do correlate pretty well, which shows that you took good data/numbers.
Now I have to figure out how to explain this to you without getting too confused myself or confusing you trying to explain it....
